This frame grab from video provided on Tuesday April 4, 2017, by Qasioun News Agency, that is consistent with independent AP reporting, shows a Syrian man carrying a man on his back who has suffered from a suspected chemical attack, in the town of Khan Sheikhoun, northern Idlib province, Syria. The suspected chemical attack killed dozens of people on Tuesday, Syrian opposition activists said, describing the attack as among the worst in the country's six-year civil war. (Qasioun News Agency, via AP)

PHOENIX — U.S. Sen. John McCain (R-Ariz.) said Tuesday that a suspected chemical attack by the Syrian government is akin to those carried out by some of the most fearsome dictatorships in history.

“These are war crimes on a scale almost unmatched since Nazi Germany or (former Cambodian leader) Pol Pot,” McCain said in an interview with CNN.

The attack Tuesday, in Khan Sheikhoun in Idlib province, is believed to have killed dozens of people. Activists on the ground described the attack as among the worst in the country’s six-year civil war.

McCain said the United States should step in and help Syria overthrow leader Bashar al-Assad, whose government is allegedly behind the chemical attack.

“The United States is going to be on the side of people who fight for freedom and we will not sit by and watch chemical weapons being used to slaughter innocent women and children,” the senator said.

The White House has condemned the suspected attack, calling it a heinous crime. But McCain said he wants President Donald Trump to do more and say he will arm the Free Syrian Army, remove Assad from office and make others — specifically Russia, Iran and terror group Hezbollah — pay for their involvement in the civil war.

“None of us are arguing for American troops on the ground there to fight against Bashar al-Assad, but we certainly believe we can fight ISIS and we can help people who are struggling against … one of the great brutal dictators in history,” he said.

McCain said inaction by the White House is the same as former President Barack Obama’s promise to make Syria pay if it crossed the red line, though he later failed to follow through on his words.